Propelling device for ships



Feb. 28, 1939. I N N 2,149,155

PROPELLING DEVICE FOR SHIPS Filed April 25, 1938 3 Sheets-Sheet 2 FIGURE6 FIGURE 8 AF? Anderson INVENTOR.

BY WWW ATTORNEY.

Feb. 28, 1939. A. F. ANDERSON PROPELLING DEVICE FOR SHIPS Filed April25, 1938 S Sheets-Sheet 3 Q mmbwbl AFTAnderson INVENTOK ATTORNEY.

Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE 'lClaims.

This invention relates to improvements in ships propellers of the typeemploying a thrust casin having a passageway or conduit extendingentirely through it in the direction of travel and in which ispositioned an impeller which operates to produce a flow of water orother fluid through it and to expel the same at the discharge end at anincreased velocity.

This invention relates more particularly to an improvement in thepropeller shown and described in U. S. Letters Patent No. 2,112,948,granted to me on April 5, 1938.

It is well known that the resistance which a body offers to movementthrough water or air can be greatly modified by its shape and bodieswhich are shaped to offer the least resistance are said to bestreamlined.

It is an object of this invention to produce a propeller thrust casingdesigned to offer a mini- 90 mum of resistance to movement through afluid.

In propellers of the type here under consideration, a thrust casing isattached to the hull of the vessel to be propelled, usually to thebottom of a ship and in any other suitable position on an airship. Thecasing is provided with a passageway extending in the general directionof ship travel, and through which the water or air is flowed under theaction of an impeller positioned therein, the cross sectional area ofthe passage:

way being greatest at the inlet and decreasing progressively towards thedischarge opening, the ratio of the areas of the intake and thedischarge openings being preferably 2 to 1. Since the same quantity ofwater flows past any given transverse plane in the same time, itisevident that the velocity at the discharge is twice that at the intakeand the passageway is so designed that the increase in velocity isattained by continuous positive acceleration.

The efiicie'ncy of a propeller of the type here under consideration isdependent, to a great extent, on the type of impeller used and on theposition of the impeller, relative to the flow of fluid. It is alsodesirable to employ a construction in which the impeller is notsubjected to any thrust in the direction of its axis of rotation, as itis in screw propellers. By avoiding end thrust, thrust bearings can'bedispensed with.

It has been found that by positioning an impeller, of the centrifugalpump type, in the casing, and in the passageway, in such a manner. thatits plane of rotation is inclined to the direction of a line joining thecenters of the inlet and the discharge openings and inwhich the fluidenters the eye of the impeller and leaves the impeller chamber at theperipheral edge thereof I nearest the discharge opening, all as will behereinafter described and shown on the drawings, an

- increased efllciency is obtained. so Having-thus, in a general way,described the with'the axis of rotation of the impeller.

Y A-A Fig. 1;

Figure 3 is a section taken on line CC Fig. 1; 10 Figure 4 is a sectiontaken on line 3-3 Fig. 2; Figure 5 is a section taken on line D-D Fig.1; Figure 6 is a side elevation of a propeller unit, showing the samemounted for rotation in an opening in the ship's bottom; 15

Figure 7 is a bottom plan view of the propelling .unit shown in Fig. 6;

Figure 8 is a fragmentary vertical section through the discharge end ofthe casing, showing adjustable means for varying the cross-sectionalareas of the outlet; and

Figure 9 is a section, on a vertical plane, through a propeller unitdesigned for use on airships.

In the drawings reference numeral ll designates a portion of the framecomprising the bottom ll of a ship. The ships bottom has a rectangularopening for the propeller that has been designated in its entirety bynumber II. The propeller assembly comprises a frame of rectangularshape, having an outer frame member I3 provided along its upper edgewith an outwardly extending flange ll that overlaps the upper flatsurface lSof the frame II. The propeller assembly is secured in place bysuitable bolts or 35 other means that have not been shown.

Supported by the frame of the assembly is a thrust casing whose bottomhas been designated by number I 6 and whose sides have been designatedby number I'I. Extending longitudinally through the casing is a ewaycomprising three sections A, B and C, designating respectively theinlet, the impeller chamber and the discharge opening. The passageway,section A, is enclosed by side walls It and a top I! and has 4 avertical partition 20 that divides it into two parts and terminates ina'circular opening 2| that is concentric with the impeller and throughwhich water or other fluid flows into the eye of the impeller. Theimpeller chamber B is formed by an enlargement of the passageway and itsplane is upwardly and forwardly inclined with respect to a line joiningthe centers of the intake and the outlet openings. In the drawings theinlet section A of the eway has been 55 shown as upwardly and rearwardlycurved and its axis, at the opening II, is practicalk pang impellerhousing has a removable section 2!,

provided withflangecll tbatfltagainltflamec so 24. The removable sectionhas an axial opening 25 through which the impeller shaft 28 extends,

astuflingboxflservestopreventleakageat this point. Section 22 has spacedintegral portions 28 that connect it with an annular end member 2! towhich the electric motor II is attached. Themotorisalsoattachedtoabace3i. Secured to the forward end of shaft 2' is an impeller 32 havingcurved vanes 33. Hg. 3.

The impeller chamber has a special conduitflanditsbottomcommunicateswiththedischarge section of the Theimpellerisusuallyrotatedinthedirectionofthearrowinl'lg.3andproducesaflowotfluidtmm the inlet to the outlet. It willbe observed that the discharge from the impeller chamber takes place atits lowest point and in a direction approximately parallel with theplane of impeller rotation, the discharge section 0 of the passagewayslopes downwardly and in a gen tle curve as shown in Fig. 1.

In order to prevent turbulence, to change the direction of the fluid andto receive thrust forces, the discharge pmage has been provided with aplurality of thrust vanes It whose inner, or forward ends are curved inthe opposite direction to that in which the impeller rotates. Theresultants of the forces acting on the fluid at this point are resistedby the curved ends of vanes Ii.

From Fig. 4 it will be seen that the vertical depth of the dischargesection C decreases in the direction of impeller rotation. This is forthe purpose of inducing a greater proportion of fluid to flowout whilemaking the least change in its direction of flow.

The velocity of the buid flowing through the propeller is usually veryhigh and on this account the passageway is not made unnecessarily long;as the loss of efliciency from this source is directly proportional toits length.

However, this loss is more than compensated for in some instances; aswhen engines having horizontal power shafts are employed and theimpeller and chamber must be accommodated to this pomtion, the way thenis extended and circinnvoluted accordingly; but its cross sectionalareas are pmsressively changed to produce the required continuousacceleration of the fluid; otherwise. losses of energy are incurredwhich reduce the efliclency of the propeller still further.

In the embodiment of the invention illustrated inFigs.lto5,thecasingisnotrotatablebutis fixed and it can therefore not be usedto steer the ship but only to propel it. Let us assume that thepropeller described above is attached to an ocean going ship The ethrough the casing is always full of water since the casing is immersed.

When the impeller is rotated in the direction indicated by the arrow inFig. 3, water is forced to flow from the intake to the outlet and, sincethe, cross sectional area of the eway decreases towards the'dischargeend to an area substantially one-hall of that of the intake opening, thewater will be increased in velocity twofold. This increase isaccomplished by a gradual decrease in the cross sectional area of thepassageway and results in a continuous positive increase inacceleration. 'Ihe force requiredtoacceleratethewatervariesdirectlyastheacceleration and the energy withthe mass and the square of the velocity. It is evident that the velocityat which the water is discharged has a great meet on the more 1cm butserious practical considerations make it more economical to move agreater mass than to employ very high velocities.

Although these propellers operate at their maximum efllciency, whichcorresponds to a theoretical condition representing 100% efllciency,whenthewateroriluid is at velocities or twice that of the ship. yet itis sometimesdesirabletochangetheratiobetweenthe areasoftheintakeandthewtletopenings andhillgjasimplemeansforthislllrmehasbeen shown. In the modifledconstruction shown in Fig.8,theupperwalloi'thedischargesection0 of the 1is provided with reaction 38 thatcanberockedaboutthepivotfl. Abolt 38isattached totheuppersurface ofthe movable section by a pivot II andextends through astufllngboxllintotheship. hunt is moimted for rotationin a bracket 42 and is held from longitudinal movement by circularflanges. When the nut is rotated bolt 38 movesupordowninaccordancewiththedirection of rotation and this varies thecross sectional area of the outlet.

It is sometimes desirable to be able to use the propeller for steeringthe ship and when this is desired the propeller frame is made roundinstead of square and is mounted for rotation in a round opening in theship's bottom. In Fig. 6 the frame "a is circular and is provided withan annular flange I! that is positioned in a groove in the frame Ila.The propeller frame is provided around its upper edge with a worm gearthatisengagedbyaworm lisecuredbetween suitable bearings attached to theship. When the worm is rotated the propeller frame is turned about avertical axis. Means for rotating the worm has not been shown but anysuitable mechanism such as is used for rudder control can be used. It isevident that when the propeller is rotatable, a rudderbecomesunnecessary.

In Fig. 9 I have shown how a propeller of thetypeabovedescribedcanbeappliedtoanairship and substituted for theordinary propeller.

Numeral l6 designates the nacelle in which is positioned the motor 41.Shaft 28a carries an impeller 32. The inlet section of the fluid passagewhich corresponds to section A in Fig. l, hasbeendasAoandisshortandstraight with forwardly flared wall. The outlet Ca communicates with theimpeller chamber Be at the lowest point thereof and curves rearwardlysothattheairwillbedischarged rearwardly along the nacelle suri'ace.'

In addition to having a propeller at the nose, others may be provided atvarious places as indicated by numeral "a.

It will be seen from the above description that the propeller formingthe subject matter is dei ned for efllclency and simplicity, that itdoes not impose its propulsive thrust on the impeller shaft and that itsinstallation is more easily eilected than the ordinary screw propellerand the maximum efllciency attainable is greater.

with the shape of blades used in the type of impeller shown in Fig. 3.the direction 01 flow oi the fluid can be reversed by reversing thedirec= Having described the invention what is claimed as new is:

1. A ship propulsion mechanism comprising in combination, an elongatedcasing having a passageway extending longitudinally therethrough andadapted to be secured to a ship, one end of the passageway being theinlet and the other end the outlet, a line joining the centers of theinlet and the outlet being substantially parallel with the direction ofships travel, the cross sectional area of the passageway decreasingprogressively from the inlet to the outlet opening, in a manner toproduce continuous acceleration of a fluid flowing therethrough, aportion of the passageway forming an impeller chamber, an impeller ofthe radial discharge centrifugal type, mounted for rotation in thechamber, the axis of rotation of the impeller being upwardly andforwardly inclined with respect to the direction of travel, and meansfor changing the cross sectional area of the outlet whereby the velocityof discharge can be varied.

2. A ship propeller mechanism, comprising in combination, an elongatedcasing having a passageway extending therethrough in the direction ofship travel, the front end serving as the intake for water and the rearend as the outlet, the wall of the passageway having an enlarged zoneserving as an impeller chamber, positioned at an intermediate point, theplane of the zone being upwardly inclined in the direction of theintake, an impeller mounted to rotate in the enlarged zone about a powershaft upwardly inclined in the direction of the outlet, the casinghaving a portion of the impeller chamber wall removable, the removableportion having an opening for the power shaft, the intake and thedischarge openings being aligned with the direction of ships travel, theunder wall surface of the intake and discharge openings connectingrespectively with the eye and the lowermost portion of the impellerchamber by curved portions.

3. An elongated propeller thrust casing adapted to be attached to aship, the casing being exteriorly streamlined to reduce resistance tbmovement through water to a minimum, the casing having a passagewayextending from one end to the other in the direction of ships travel,the endsof the passageway being substantially parallel, means comprisinga fluid impeller positioned in the passageway for acting upon watercontained therein to increase its velocity, said impeller beingrotatable in a plane upwardly inclined in the direction of the intake,the outlet being below the lower edge of the impeller, means comprisingwalls having curved surfaces, for changing the direction of the fluidstream as it leaves the impeller, means comprising the walls of theintake opening to direct the fluid to the eye of the impeller, thepassageway decreasing in cross section from the intake to the dischargewhereby the fluid passing through the same will be increased in velocityfrom intake to outlet, and means comprising a pivoted wall section forchanging the cross sectional area of the outlet p ning.

4. A hydraulic propeller unit for attachment to a ship's hullhaving anopening in its bottom comprising a frame having an outwardly extendingflange for supporting the frame in the opening, a thrust casing attachedto the frame, the casing having a passageway, the intake and thedischarge openings of the passageway being located below the level ofthe under surface of the frame, a portion of the passageway beingenlarged to form an impeller chamber, both ends of the passagewaycurving upwardly towards the impeller chamber, a single eye impeller inthe chamber, mounted for rotation about an axis substantially parallelwith the axis of the communicating end of the intake passage, the upperend of the discharge passage being substantially parallel with the planeof rotation of the impeller.

5. A ship propulsion mechanism comprising, in combination, a casinghaving a passageway extending therethrough and adapted to be attached toa ship, one end of the passageway being the inlet and the other end theoutlet, a line joining the centers of the inlet and the outlet beingsubstantially parallel with the direction of ship travel, the crosssectional areas of the passageway decreasing progressively from theinlet to the outlet opening in a manner to produce continuousacceleration of a fluid flowing therethrough, a portion of thepassageway forming an impeller chamber, an impeller of the radialdischarge centrifugal type operatively mounted in the chamber, and meansfor changing the cross sectional area of the outlet whereby the velocityof discharge can be varied.

6; A ship propeller mechanism, comprising, in combination, a casinghaving a passageway extending therethrough in the direction of shiptravel, the front end serving as the intake and the rear end as theoutlet, the passageway having an enlarged zone serving. as an impellerchamber, positioned at an intermediate point, an impeller mounted torotate in the enlarged zone, a power shaft passing through the casingwall and operatively connected with the impeller, the casing having aportion of the impeller chamber wall removable, the removable portionhaving an opening for the power shaft, the intake and outlet openingsbeing aligned with the direction of ship travel, the intake and outletopenings connecting respectively with the eye and the peripheral portionof the impeller chamber by passageways having curved walls.

'7. In combination with a ship having an opening in the bottom of itshull, a propulsion apparatus positioned in the'opening, said apparatuscomprising a thrustcasing having a passageway extending therethrough,one end forming an inlet and the other the outlet, the distance betweenthe inlet and the outlet being less than the corresponding dimensions ofthe opening whereby the casing may be inserted from the inside of theship, an intermediate portion of the passageway being enlarged to forman impeller chamber, a line joining the inlet and outlet openings beingsubstantially parallel with the direction of ship travel, a continuouswall attached to the casing above the inlet and outlet opening, the wallbeing of a size and shape to fit the opening in the hull, the upper edgeof the wall having an outwardly extending element for projecting overthe wall of the opening in the ships. hull to support the casing, theinlet and outlet openings being positioned wholly below the hull, thepassageways connecting the inlet and outlet openings curving upwardly toan impeller chamber which is positioned within the hull, the portion ofthe casing below the hull being streamlined.

ALBERT F. ANDERSON.

